Image display

ABSTRACT

The present invention provides an image display system in which an image can be seen from positions other than predetermined viewing position. The image display system includes optical means for allowing light from a backlight ( 810 ) to be transmitted to a left eye image area and a right eye image area and causing the transmitted lights from the respective image areas to enter into a left eye and a right eye of an viewer independently, and image parallax switching means for selectively displaying an image for three-dimensional display which causes parallax between both eyes of the viewer when displaying a three-dimensional image to the viewer or an image for two-dimensional display which does not cause parallax between the both eyes of the viewer when displaying a two-dimensional image to the viewer on the display area, auxiliary light sources ( 814 ) for irradiating a liquid crystal display panel ( 804 ) and causing the irradiated light to be transmitted through the left eye image area or the right eye image area and enter into the both eyes of the viewer and light source control means which turns on the backlight ( 810 ) when showing the three-dimensional image to the viewer and turns on the auxiliary light sources ( 814 ) when showing the two-dimensional image to the viewer are provided.

TECHNICAL FIELD

The present invention relates to an image display system which candisplay an a three-dimensional image.

BACKGROUND ART

Hitherto, an image display system for displaying a stereoscopic image(three-dimensional image) by displaying an right-eye image and aleft-eye image having parallax using a liquid crystal display unit orthe like is known (JP-A-10-63199, etc.).

[Patent Document 1] JP-A-10-63199

However, in the related art, since it is intended only to show thethree-dimensional image to a viewer, the viewing angle is set to a smallangle. Therefore, those who are not in the viewing angle cannot see theimage, or the image appears to be extremely dark. In such an imagedisplay system, there is a problem that a wide viewing angle cannot beachieved due to the structure of an optical system thereof, when ademonstrative display for collecting people in front of the imagedisplay system is desired for people viewing from points other than apredetermined viewing zone set in front of the image display system,which may pose an impediment when appealing characteristics of the imagedisplay system.

DISCLOSURE OF THE INVENTION

In view of the problem described above, it is an object of the presentinvention to provide an image display system which can view an imagealso from a position other than a predetermined viewing zone.

A first aspect of the invention is an image display system including aliquid crystal display panel being irradiated by a backlight and havinga left eye image area and a right eye image area respectively on adisplay panel, optical means for allowing light from the backlight to betransmitted to the left eye image area and the right eye image area andcausing the transmitted lights from the respective image areas to enterinto a left eye and a right eye of an viewer independently, and imageparallax switching means for selectively displaying an athree-dimensional image which causes parallax between both eyes of theviewer when showing the three-dimensional image to the viewer or atwo-dimensional image which does not cause parallax between both eyeswhen showing the two-dimensional image to the viewer on the displayarea, wherein an auxiliary light source for irradiating the liquidcrystal display panel and causing the irradiated light to be transmittedthrough the left eye image area or the right eye image area and enterinto the both eyes of the viewer and light source control means whichturns on the backlight when showing the three-dimensional image to theviewer, and turns on the one or a plurality of auxiliary light sourceswhen showing the two-dimensional image to the viewer are provided.

In the first aspect of the invention, a second aspect of the inventionis characterized in that when the image parallax switching meansswitches the image to be shown to the viewer from the three-dimensionalimage to the two-dimensional image, the one or a plurality of auxiliarylight sources are turned on by the light source control means afterswitching to display from the three-dimensional image to thetwo-dimensional image by the image parallax switching means.

In the first and second aspects of the invention, a third aspect of theinvention is characterized in that when the image parallax switchingmeans switches the image to be shown to the viewer from thetwo-dimensional image to the three-dimensional image, the display isswitched from the tow-dimensional image to the three-dimensional imageby the image parallax switching means after turning off the one orplurality of auxiliary light sources by the light source control means.

In one of the first to third aspects of the invention, a fourth aspectof the invention is characterized in that the light source control meansturns off or dims the backlight when the one or a plurality of auxiliarylight sources are turned on.

In one of the first to third aspects of the invention, a fifth aspect ofthe invention is characterized in that the light source control meansalso turns on the backlight when turning on the one or a plurality ofauxiliary light sources.

In one of the first to fifth aspects of the invention, a sixth aspect ofthe invention is characterized in that the one or a plurality ofauxiliary light sources are higher in brightness than the backlight.

In one of the first to sixth aspects of the invention, a seventh aspectof the invention is characterized in that the backlight is disposedbetween the liquid crystal display panel and the one or a plurality ofauxiliary light sources.

In one of the first to seventh aspects of the invention, an eighthaspect of the invention is characterized in that the one or a pluralityof auxiliary light sources are composed of one or a plurality of surfacelight sources.

In one of the first to eighth aspects of the invention, a ninth aspectof the invention is characterized in that viewer detection means fordetecting existence of the viewer, and the light source control meansturns on the one or a plurality of auxiliary light sources when theexistence of the viewer is not detected by the viewer detection means.

Therefore, according to the first aspect of the invention, the clearthree-dimensional image can be provided by the backlight whichirradiates a light for the left eye and a light for the right eyeindependently when displaying the three dimensional image, while thetwo-dimensional image with a wide viewing angle can be displayed by theone or a plurality of auxiliary light sources which irradiates the lighttransmitting through both the left eye image area and right eye imageareas and reaching both eyes of the viewer when displaying thetwo-dimensional image, whereby an optimal image (a three-dimensionalimage or a two dimensional image) depending on the position of theviewer can be displayed.

According to the second aspect of the invention, since the one or aplurality of auxiliary light sources are turned on by the light sourcecontrol means after switching the three-dimensional image thetwo-dimensional image, generation of cross-talk in the three-dimensionalimage is avoided by preventing the left-eye image and the right-eyeimage from reaching the both eyes by the one or a plurality of auxiliarylight sources which widens the viewing angle, and switching from thethree-dimensional image to the two-dimensional image is achieved withoutgiving a feeling of discomfort to the viewer.

According to the third aspect of the invention, since switching to thethree-dimensional image is performed after the one or a plurality ofauxiliary light sources are turned off, both of the left-eye image andthe right-eye image reach both eyes by illuminating the one or aplurality of auxiliary light sources. Therefore, by switching to thethree-dimensional image after causing the light from the backlight toreach the both eyes of the viewer by turning off the one or a pluralityof auxiliary light sources, generation of the cross-talk in the left-eyeimage and the right-eye image is reliably prevented, and hence switchingfrom the image for two-dimensional display to the image forthree-dimensional display can be performed smoothly without giving asense of discomfort to the viewer.

According to the fourth aspect of the invention, since the backlight isturned off or dimmed when turning on the auxiliary light source,durability of the device can be improved by controlling heat generationof the light source and promotion of energy saving is achieved bycontrolling power consumption.

According to the fifth aspect of the invention, since the backlight isalso turned on when turning on the auxiliary light source, the angle ofvisibility when displaying the image for two-dimensional display can beenlarged by increasing the light amount transmitting through the liquidcrystal display panel.

According to the sixth aspect of the invention, since the auxiliarylight source is higher in brightness than the backlight, the angle ofvisibility when displaying the image for two-dimensional display can beenlarged.

According to the seventh aspect of the invention, since the backlight isdisposed between the liquid crystal display panel and the auxiliarylight source, the lights for the left eye and for the right eye can beincident into the liquid crystal display panel without being interceptedby the auxiliary light source.

According to the eighth aspect of the invention, since the auxiliarylight source is composed of the surface light source, the light amountcan further be increased to enlarge the angle of visibility whendisplaying the image for two-dimensional display.

According to the ninth aspect of the invention, when the existence ofthe viewer is not detected by the viewer detection means, the auxiliarylight source is turned on to enlarge the angle of visibility, so thatthe viewer can view from a range larger than that for the image forthree-dimensional display.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view showing an optical system of animage display system according to an embodiment of the presentinvention.

FIG. 2 is a block diagram showing a control system of the same.

FIG. 3 is a plan view of the optical system of the same.

FIG. 4 is a flowchart showing an example of light source control.

FIG. 5 is an exploded perspective view showing the optical system of theimage display system according to another embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to the drawings, an embodiment of the present inventionwill be described.

FIG. 1 is an exploded perspective view showing an optical system of animage display system according to an embodiment of the presentinvention.

FIG. 2 is a block diagram showing a control system of the same.

FIG. 3 is a plan view of the optical system of the same.

FIG. 4 is a flowchart showing an example of light source control.

FIG. 5 is an exploded perspective view showing the optical system of theimage display system according to another embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to the drawings, an embodiment of the present inventionwill be described.

FIG. 1 shows an example of an image display system 8 to which thepresent invention is applied, and a light source 801 (main light source)includes a light emitting device 810, a polarizing filter 811, and aFresnel lens 812.

The light emitting device (backlight) 810 as a main light source iscomposed of a point light source such as white light emitting diode(LED) or linear light sources such as cold-cathode tube arranged inparallel. The polarizing filter 811 consists of a left area 811 b and aright area 811 a which are adapted to provide different polarizations tolights transmitting therethrough (for example, to differentiate betweenthe polarization axes of the lights transmitting through the left area811 b and the right area 811 a by 90 degrees). The Fresnel lens 812 hasa lens surface having a concentric microstructures on one side.

Only the light emitted from the light emitting device 810 and havingpredetermined polarizations can be transmitted through the polarizingfilter 811. In other words, the light emitted from the light emittingdevice 810 which is passed through the left area 811 b of the polarizingfilter 811 and the light passed through the right area 811 a thereof areirradiated on the Fresnel lens 812 as lights having differentpolarizations. As will be described later, the light passed through theleft area 811 b of the polarizing filter 811 reaches the right eye ofthe viewer, and the light passed through the right area 811 a reachesthe left eye of the viewer.

It is not necessarily required to use the light emitting device and thepolarizing filter, and it's only necessary that the lights of differentpolarizations be irradiated from different positions. For example, itmay be adapted in such a manner that two light emitting devicesgenerating lights of different polarizations are provided so that thelights of different polarization are irradiated to the Fresnel lens 812from different positions.

The lights transmitted through the polarizing filter 811 are irradiatedon the Fresnel lens 812. The Fresnel lens 812 is a convex lens, andrefracts optical paths of light emitted from the light emitting device810 in a diffusing manner into substantially parallel lights, thenallows the same to pass through a micro-patterned half wave retarder 802and then to be irradiated onto a liquid crystal display panel 804.

At this time, the light irradiated through the micro-patterned half waveretarder 802 is emitted so as not to diffuse in the vertical direction,and is irradiated on the liquid crystal display panel 804. In otherwords, the light transmitted through a specific area of themicro-patterned half wave retarder 802 is transmitted through specificunits of display of the liquid crystal display panel 804.

Regarding the lights irradiated to the liquid crystal display panel 804,the light passing through the right area 811 a of the polarizing filter811 and the light passing through the left area 811 b thereof areincident onto the Fresnel lens 812 at different angles, are refracted bythe Fresnel lens 812, and are emitted from the liquid crystal displaypanel 804 along the left and right paths respectively.

The liquid crystal display panel 804 is provided with liquid crystalcomprising liquid crystal molecules oriented and twisted at apredetermined angle (for example, 90 degrees) and disposed between twotransparent plates (for example, glass plates), to form, for example, ofa TFT type liquid crystal display panel. The light incident upon theliquid crystal display panel is emitted with a polarization axis rotatedby 90 degrees in a state in which no voltage is applied to the liquidcrystal. On the other hand, when a voltage is applied to the liquidcrystal, twisting of the liquid crystal is released, and the incidentlight is emitted without changing the polarization.

The micro-patterned half wave retarder 802 and a polarizing plate 803(second polarizing plate) are disposed on the side of the light source801 of the liquid crystal display panel 804, and a polarizing plate 805(first polarizing plate) is disposed on the viewer side.

The micro-patterned half wave retarder 802 includes regions which changethe phase of light ray transmitting therethrough disposed at fineintervals repeatedly.

More specifically, a light transmitting base material is formed withregions 802 a having the first polarization characteristics of a minutewidth, and regions 802 b each having the same width as the width of theregions 802 a and having the second polarization characteristicsdifferent from the first polarization characteristics, and arranged atminute intervals repeatedly.

In other words, the regions 802 a which have the first polarizationcharacteristics and change the phase of light transmitting therethroughby the ½ wave plates provided at minute intervals and the regions 802 bwhich have the second polarization characteristics same as thepolarization characteristics of the transmitting light and do not changethe phase of light ray transmitting therethrough since the ½ wave plates821 are not provided are arranged repeatedly at minute intervals.

The regions 802 a are disposed so that the optical axis thereof isinclined by 45 degrees with respect to a polarization axis of the lighttransmitting through the right area 811 a of the polarizing filter 811,thereby emitting the light transmitted through the right area 811 a withits polarization axis rotated by 90 degrees.

In other words, polarization axis of the light transmitting through theright area 811 a is rotated by 90 degrees to equalize to that of thelight transmitting through the left area 811 b. In other words, theregions 802 b having the second polarization characteristics are notprovided allow lights passed through the left area 811 b and having thesame polarization as the polarizing plate 803 to be transmittedtherethrough. The regions 802 a having the first polarizationcharacteristics cause the light passed through the right area 811 a andhaving the polarization axis orthogonal to the polarizing plate 803 tobe rotated so as to equalize the polarization axis thereof to that ofthe polarizing plate 803 before emission.

The array of regions of each polarization characteristics of themicro-patterned half wave retarder 802 is adapted to have substantiallythe same pitch as the unit of display of the liquid crystal displaypanel 804 to differentiate polarization of the lights transmittedtherethrough by each unit of display (that is, by each horizontal lineof the unit of display). Therefore, the polarization characteristics ofthe micro-patterned half wave retarder 802 are differentiated for eachof the corresponding horizontal lines (scanning line) as the unit ofdisplay of the liquid crystal display panel 804, whereby the directionsof lights emitted from the adjacent horizontal lines are different.

Alternatively, the array of the regions having the polarizationcharacteristics of the micro-patterned half wave retarder 802 may have apitch which is integral multiple of the pitch of the unit of display ofthe liquid crystal display panel 804, so that the polarizationcharacteristics are differentiated for each set of a plurality of unitsof display on the micro-patterned half wave retarder 802 (that is, foreach set of the plurality of horizontal lines as the unit of display),thereby differentiating the polarization of the lights transmittedtherethrough for each set of the plurality of units of display. In thiscase, the polarization characteristics of the micro-patterned half waveretarder are different for each set of the plurality of horizontal linesas the unit of display (scanning lines), and hence the directions of theemitted lights are different for each set of plurality of horizontallines.

In this case, since it is necessary to irradiate differently polarizedlights onto the adjacent units of display of the liquid crystal displaypanel 804 (horizontal lines) for each region having a polarizationcharacteristics of the micro-patterned half wave retarder 802, thelights to be irradiated on the liquid crystal display panel 804 aftertransmitting through the micro-patterned half wave retarder 802 must becontrolled to diffuse vertically.

In other words, the regions 802 a of the micro-patterned half waveretarder 802 for changing the phase of the light change the lighttransmitting through the right area 811 a of the polarizing filter 811to have the same inclination of the polarization axis as the lighttransmitting through the left area 811 b. On the other hand, the regions802 b of the micro-patterned half wave retarder 802 which have thesecond polarization characteristics allow the light transmitting throughthe left area 811 b of the polarizing filter 811 to transmitted as is.Then, the lights emitted from the micro-patterned half wave retarder802, having the same polarizations of the light transmitting through theleft area 811 b, are incident upon the polarizing plate 803 provided onthe light source side of the liquid crystal display panel 804.

The polarizing plate 803 functions as the second polarizing plate, andhas such polarization characteristics as to allow light having the samepolarization as the light having transmitted through the left area 811 bof the polarizing filer 811 to be transmitted. In other words, the lighttransmitting through the left area 811 b of the polarizing filter 811 istransmitted through the second polarizing filter 803, and the polarizingaxis of the light transmitting through the right area 811 a of thepolarizing filter 811 is rotated by 90 degrees before transmittingthrough the second polarizing plate 803. The polarizing plate 805functions as the first polarizing plate, and has such polarizingcharacteristics as to allow light having a polarization different fromthe polarizing plate 803 by 90 degrees to be transmitted therethrough.

The micro-patterned half wave retarder 802, the polarizing plate 803,and the polarizing plate 805 are bonded together to the liquid crystaldisplay panel 804, and the micro-patterned half wave retarder 802, thepolarizing plate 803, the liquid crystal display panel 804, and thepolarizing plate 805 are combined to constitute the image displaysystem. At this time, in a state in which a voltage is applied to theliquid crystal, the light transmitting through the polarizing plate 803is transmitted through the polarizing plate 805. On the other hand, in astate in which no voltage is applied to the liquid crystal, the lighttransmitting through the polarizing plate 803, whereof the polarizationis twisted by 90 degrees, is emitted from the liquid crystal displaypanel 804, and hence does not transmit through the polarizing plate 805.

A diffuser 806 is mounted to the front side (viewer side) of the firstpolarizing plate 805, and functions as diffusing means for diffusing thelight transmitting through the liquid crystal display panel in thevertical direction. More specifically, it diffuses the lighttransmitting through the liquid crystal display panel in the verticaldirection using a lenticular lens having projections and depression ofsemicircular shape in cross-section provided repeatedly in the verticaldirection.

Instead of the lenticular lens, the one provided with a mat diffusingsurface having stronger diffusing property in the vertical directionthan in lateral direction. It can improve a disadvantage that theviewing angle is narrowed by diffusion control in the vertical directionuntil the light is completely transmitted through the liquid crystaldisplay panel 804.

In addition, the one or a plurality of auxiliary light sources 814 aredisposed behind the light emitting device 810 as a main light source.The one or a plurality of auxiliary light sources 814 include aplurality of electric bulbs or a plurality of light emitting devices(LED or EL) or the like, which are turned on when the image is desiredto be viewed by many viewers and increase the light amount transmittedthrough the liquid crystal display panel 804, thereby enlarging theviewing angle of a screen of the image display system 8.

Therefore, the lights from the one or a plurality of auxiliary lightsources 814 are not required to pass through the polarizing filter 811,and goes through the Fresnel lens 812, the micro-patterned half waveretarder 802, the polarizing plate 803, the liquid crystal display panel804, the polarizing plate 805, and then the diffuser 806 to reachviewers or working staff in the vicinity of the viewers.

Then, since most of the light from the one or a plurality of auxiliarylight sources 814 is diffusive light which has not passed through thepolarizing filter 811, the light can be irradiated entirely on theliquid crystal display panel 804 to improve the brightness of thedisplay system 8 to widen the viewing angle of the secondary image.

FIG. 2 is a block diagram showing a drive circuit of an image displaysystem according to an embodiment of the present invention.

A main control circuit 100 for driving the image display system 8according to the embodiment of the present invention includes a CPU 101,a ROM 102 having a program or the like stored therein in advance, and aRAM 103 as a memory used as a work area when the CPU 101 is inoperation. The CPU 101, the ROM 102, and the RAM 103 are connected by abus 108. The bus 108 includes an address bus and a data bus which areused when the CPU 101 reads and writes data.

A communication interface 105, an input interface 106, and an outputinterface 107, which perform input and output with respect to theoutside, are connected to the buss 108. The communication interface 105is a data input/output section for data transmission according to apredetermined communication protocol. The input interface 106 and theoutput interface 107 input and output image data to be displayed on theimage display system 8.

An viewer detection sensor 300 for detecting whether or not an viewer ispresent at a position from which the viewer can see a three-dimensionalimage and in a range in which the viewer can see the image displaysystem 8 is connected to the input interface 106. The viewer detectionsensor 300 includes an infrared ray sensor, a motion sensor, or apressure sensor or the like which is provided on a seat or the like.

A graphic display processor (GDP) 156 of a display control circuit 150is connected to the bus 108. The GDP 156 calculates image data generatedby the CPU 101, writes the same to a frame buffer provided in the RAM153, and generates signals (RGB, V BLANK, V_SYNC, H_SYNC) to beoutputted to the image display system 8. The ROM 152 and the RAM 153 areconnected to the GDP 156, and the RAM 153 is provided with a work areawhere the GDP 156 works and the frame buffer for storing the displaydata. The ROM 152 includes a program and data required for the operationof the GDP 156.

The GDP 156 includes an oscillator 158 for supplying a clock signal tothe GDP 156 connected thereto. The clock signal for generating theoscillator 158 defines the operating frequency of the GDP 156 andgenerates a frequency of the synchronized signal outputted from the GDP156 (for example, V_SYNC, V BLANK).

The RGB signal outputted from the GDP 156 is inputted to a γ correctivecircuit 159. The γ corrective circuit 159 corrects a non-linearcharacteristic of brightness with respect to the signal voltage of theimage display system 8, adjusts the illumination brightness of displayof the image display system 8, and generates the RGB signal outputted tothe image display system 8.

A combining and converting device 170 is provided with a frame bufferfor right-eye, a frame buffer for left-eye and a frame buffer forviewing a three-dimensional image, and writes a right-eye image sentfrom the GDP 156 in the frame buffer for right-eye, a left-eye image tothe frame buffer for left-eye. Then, the combining and converting devicecombines the right-eye image and the left-eye image to generate thethree-dimensional image, and writes the same in the frame buffer forviewing the three-dimensional image, and outputs the image data forthree-dimensional view to the image display system 8 as a RGB signal.

Generation of the three-dimensional image by combining the right-eyeimage and the left-eye image is done by combining the right-eye imageand the left-eye image according to the regions 802 a and 802 b of themicro-patterned half wave retarder 802. More specifically, since theregions 802 a and 802 b of the micro-patterned half wave retarder 802 ofthe image display system 8 according to the present embodiment aredisposed at intervals of the unit of display of the liquid crystaldisplay panel 804, the image for viewing a three-dimensional image isdisplayed so that the right-eye images and the left-eye images arealternately displayed by each lateral line (scanning line) as the unitof display of the liquid crystal display panel 804.

The left-eye image data transmitted from the GDP 156 during output of Lsignal is written in the frame buffer for left-eye and the right-eyeimage data transmitted from the GDP 156 during output of R signal iswritten in the frame buffer for right-eye. Then, the left-eye image datawritten in the frame buffer for left-eye and the right-eye image datawritten in the frame buffer for right-eye are read out for each scanningline and written in the frame buffer for viewing a three-dimensionalimage.

The image display system 8 includes a liquid crystal driver (LCD DRV)181, a backlight driver (BL DRV) 182, and a lamp driver 183 for drivingthe one or a plurality of auxiliary light sources 814. The liquidcrystal driver (LCD DRV) 181 applies a voltage to the electrodes of theliquid crystal display panel in sequence based on the V BLANK signal,the V_SYNC signal, H_SYNC signal, and the RGB signal transmitted fromthe combining and converting device 170 to display a combined image forviewing a three-dimensional image on the liquid crystal display panel.

The backlight driver 182 changes duty ratios of voltage applied to thelight emitting device (backlight) 810 as a main light source 801 and theone or a plurality of auxiliary light sources 814 respectively based onthe DTY_CTR signal outputted from the GDP 156, thereby changingbrightness of the liquid crystal display panel 804. The DTY_CTR signal(duty ratio) for controlling the light emitting device 810 and the dutyratio for controlling the one or a plurality of auxiliary light sources814 are independent.

The lamp driver 183 controls turning on and off of the one or aplurality of auxiliary light sources 814 according to the control signal(LMP_CTR) from the CPU 151.

FIG. 3 is a plan view showing an optical system of the image displaysystem 8.

Light emitted from the light emitting device 810 is passed through thepolarizing filter 811 and is radially diffused. The light emitted fromthe light source passes through the right area 811 a of the polarizingfilter 811 (a dashed line indicates a center of the optical path) andreaches the Fresnel lens 812, where the direction of travel of the lightis changed, then is transmitted through the micro-patterned half waveretarder 802, the polarizing plate 803, the liquid crystal display panel804, and the polarizing plate 805 substantially orthogonally thereto(substantially from the right side to the left side), and then reachesthe left eye.

On the other hand, part of the light emitted from the light emittingdevice 810 which is transmitted through the left area 811 b of thepolarizing filter 811 (a broken line indicates a center of the opticalpath) reaches the Fresnel lens 812, where the direction of travel ischanged, is passed through the micro-patterned half wave retarder 802,the polarizing plate 803, the liquid crystal display panel 804, and thepolarizing plate 805 substantially in the vertical direction(substantially from the left side to the right side), and then reachesthe right eye.

In this manner, the light emitted from the light emitting device 810 andtransmitted through the polarizing filter 811 is irradiated to theliquid crystal display panel 804 by the Fresnel lens 812 as the opticalsystem substantially in the vertical direction. In other words, thelight source 801 which irradiates the lights having different planes ofpolarization onto the liquid crystal display panel 804 substantially inthe vertical direction along the different routes is configured with thelight emitting device 810, the polarizing filter 811 and the Fresnellens 812, and the light transmitted through the liquid crystal displaypanel 804 is emitted along the different routes and reaches the left eyeor the right eye.

In FIG. 3, a position indicated by a wave line in the drawing is set asa three-dimensional image viewing zone with respect to the depthdirection. The three-dimensional image viewing zone includes a referenceposition where only the light transmitting through the right area 811 aof the polarizing filter 811 enters into the viewer's left eye, and onlythe light transmitting through the left area 811 b of the polarizingfilter 811 enters into the viewer's right eye, whereby thethree-dimensional image can be recognized. Since the distance betweenthe left eye and the right eye of the viewer is different from person toperson, the three-dimensional image viewing zone is defined by theaverage value of the distance between the left and right eyes.Therefore, actually, as shown by a dashed line in the drawing, apredetermined range with respect to the depth direction of the imagedisplay system 8 corresponds to a three-dimensional image recognizablerange. The three-dimensional image viewing zone in the horizontaldirection (vertical direction in the drawing) of the image displaysystem 8 is a correct position with respect to the center of the imagedisplay system 8 in the case of FIG. 3.

In other words, by equalizing the pitch of the scanning lines of theliquid crystal display panel 804 and the pitch of the regions having thepolarization characteristics on the micro-patterned half wave retarder802, the lights coming from the different directions are irradiated oneach pitch of the scanning lines of the liquid crystal display panel 804and hence the lights are emitted in the different directions.

On the other hand, most of the lights from the one or a plurality ofauxiliary light sources 814 do not pass through the polarizing filter811, but pass through the Fresnel lens 812, the micro-patterned halfwave retarder 802, the polarizing plate 803, the liquid crystal displaypanel 804, the polarizing plate 805, and the diffuser 806 in a state ofdiffused light and reaches the viewer side. Therefore, different fromthe aforementioned light passed through the polarizing filter 811, thelights from the one or a plurality of auxiliary light sources 814display the two-dimensional image without constituting thethree-dimensional image. The two-dimensional image recognizable rangecorresponds to a range in which the viewer can see the lights passedfrom the one or a plurality of auxiliary light sources 814 through theliquid crystal display panel 804, the polarizing plate 805, and thediffuse 806, and is an extremely larger than the three-dimensional imagerecognizable range.

FIG. 4 is a flowchart of control carried out by the GDP 151, which iscarried out at predetermined intervals (for example, at intervals of acycle of vertical synchronous signals; 16.7 msec= 1/60 seconds).

In Step S1, signals from the viewer detection sensor 300 is read todetect whether or not the viewer is in the three-dimensional imagerecognizable range, and then determine whether or not the currentdetection result is changed from the previous detection result.

In Step S2, the procedure is routed according to the change of the stateof the viewer. When the state of the viewer is not changed and theviewer is not in the three-dimensional image recognizable zone, theprocedure goes to Step S3, and when the state of the viewer also isn'tchanged and the viewer is in the three-dimensional image recognizablezone, the procedure goes to Step S11. Then, regarding the case in whichthe state of the viewer is changed, when the state of the viewer ischanged from “absent” to “present”, the procedure goes to Step S6, andwhen the state of the viewer is changed from “present” to “absent”, theprocedure goes to Step S8.

In Step S3 in which the viewer is not in the three-dimensional imagerecognizable zone and the state of the viewer is not changed, the valueof the timer is renewed (for example, incremented), and in Step S4,whether or not the value of the timer has become the predetermined valueis determined. When the value of the timer has become the predeterminedvalue, the procedure goes to Step S5, where the light source controlprocess as described later is performed, and when the value of the timerhas not become the predetermined value, the procedure is ended as is.

In Step S11 in which the viewer is in the three-dimensional imagerecognizable range, and the state of the viewer is not changed,turning-on control of the light emitting device 810 as a main lightsource is performed at a predetermined duty ratio.

On the other hand, in Step S6 where the state of the viewer is changedfrom “absent” to “present”, the one or a plurality of auxiliary lightsources 814 are turned off and only the main light source 810 is turnedon, and then the procedure goes to Step S7, where the image to bedisplayed on the image display system 8 is switched from antwo-dimensional image having no parallax (two-dimensional image) to thethree-dimensional image having parallax (image for displaying athree-dimensional image).

In Step S8 where the state of the viewer is changed from “present” to“absent”, the image to be displayed on the image display system 8 isswitched from the three-dimensional image having parallax (image fordisplaying a three-dimensional image) to the two-dimensional image(two-dimensional image) having no parallax, and in Step S9, the one or aplurality of auxiliary light sources 814 are turned on to increase thelight amount which is transmitted through the liquid crystal paneldisplay 804.

Then, in Step S10, the timer is initialized (for example, zero-reset) toend the procedure.

In the light source control process performed in the above-describedStep S5, when the value of the timer exceeds a predetermined value, theone or a plurality of auxiliary light sources 814 are turned off tocontrol heat generation and power consumption of the light sources.

Alternatively, when the value of the timer exceeds a predeterminedvalue, the one or a plurality of auxiliary light sources 814 are made toblink, whereby the heat generation and the power consumption of thelight sources can be controlled while displaying the two-dimensionalimage continuously. In the one or a plurality of auxiliary light sources814 which include a plurality of the light emitting members, lightemitting members may be divided into groups and light emission controlmay be applied to those groups to make them blink alternately.

With the above-described control, when the state is changed from a statein which the viewer is “absent” to “present” in the three-dimensionalimage recognizable zone of the image display system 8, the one or aplurality of auxiliary light sources 814 are turned off and then thetwo-dimensional image is switched to the image, so that only the lightemitting device 810 as a main light source is turned on to provide thethree-dimensional image to the viewer who is present at a predeterminedposition.

At this time, since switching to the three-dimensional image is doneafter the one or a plurality of auxiliary light sources 814 are turnedoff, both of the left-eye image and the right-eye image reach the botheyes by illumination of the one or a plurality of auxiliary lightsources 814. Therefore, by switching to the three-dimensional imageafter turning off the one or a plurality of auxiliary light sources 814to cause the light from the light emitting device 810 as a main lightsource to reach the viewer's both eyes, generation of cross-talk of theleft-eye image and the right-eye image can reliably be prevented, andhence switching from the two-dimensional image to the three-dimensionalcan be performed smoothly without giving a feeling of discomfort to theviewer.

On the other hand, when the state is changed from the state in which theviewer is “present” to “absent” in the three-dimensional imagerecognizable zone of the image display system 8, the image to bedisplayed is switched from the three-dimensional image to thetwo-dimensional image, and then the one or a plurality of auxiliarylight sources 814 are turned on.

When the one or a plurality of auxiliary light sources 814 are turnedon, the brightness of the image display system 8 (the light amount ofthe liquid crystal display panel) increases and the viewing angle of theimage display system 8 increases by the diffusing light from the one ora plurality of auxiliary light sources 814 which is not passed throughthe polarizing filter 811, and hence the two-dimensional image can beprovided to the viewer who is out of the three-dimensional imagerecognizable range. Therefore, for example, demonstration images whichare intended to be viewed by unspecified viewers can be displayedeffectively.

Since it is adapted to turn on the one or a plurality of auxiliary lightsources 814 after having switched the three-dimensional image to thetwo-dimensional image, the left-eye image and the right-eye image areprevented from reaching to the both eyes due to the one or a pluralityof auxiliary light sources 814 which provide diffusing light, and hencegeneration of cross-talk in the three-dimensional image is prevented,whereby switching from the three-dimensional image to thetwo-dimensional image can be carried out without giving feeling ofdiscomfort to the viewer.

Then, when the state of “absent” is continued for a period exceeding thepredetermined value, the one or a plurality of auxiliary light sources814 can be turned off or made to blink by controlling the light source,and hence heat generation and power consumption of the light source canbe controlled.

In this manner, since it is adapted to switch between thethree-dimensional image and the two-dimensional image depending on thepresence or absence of the viewer and to turn on the one or a pluralityof auxiliary light sources 814 depending on the type of the image, thecharacteristics of the light emitting device 810 as a main light sourcefor irradiating the light for the left eye and the light for the righteye independently and the one or a plurality of auxiliary light sources814 for irradiating diffusing light and providing the wide viewing angleare selectively used as needed, so that an optimal image (athree-dimensional image or a two-dimensional image) can be displayedaccording to the position of the viewer.

Also, since the one or a plurality of auxiliary light sources 814 arearranged behind the light emitting device 810 as a main light source, inother words, since the light emitting device 810 as a main light sourceis disposed between the one or a plurality of auxiliary light sources814 and the Fresnel lens 812, the light of the light emitting device 810as a main light source can be irradiated to the Fresnel lens 812 and theliquid crystal display panel 804 as is without being intercepted by theone or a plurality of auxiliary light sources 814 when displaying thethree-dimensional image, so that the light from the light emittingdevice 810 can be transmitted to the viewer efficiently and hence theclear three-dimensional image can be provided.

In this manner, since the present embodiment is adapted to turn on theone or a plurality of auxiliary light sources 814 and the main lightsource 810 simultaneously when displaying the two-dimensional image, thelight amount transmitted through the liquid crystal display panel 804increases and hence the viewing angle can be widened, whereby the rangein which the two-dimensional image is recognizable can be widened.

It is also possible to turn off or dim the light emitting device 810 asa main light source when turning on the one or a plurality of auxiliarylight sources 814. In this case, by using only the one or a plurality ofauxiliary light sources 814 for displaying the two-dimensional image,heat generation and power consumption of the light emitting device 810as a main light source can be controlled to improve durability of thesystem and promotion of energy saving.

In the above-described embodiment, it is preferable to set thebrightness of the one or a plurality of auxiliary light sources 814higher than the brightness of the light emitting device 810 as a mainlight source, and type of the light emitting devices used for therespective light sources, the number of the light emitting devices, thecurrent or voltage to be supplied to the light emitting devices, theblinking duty ratio of the light emitting devices and so on, must beselected as needed.

In the case in which the one or a plurality of auxiliary light sources814 and the light emitting device 810 as a main light source are turnedon simultaneously when displaying the two-dimensional image, the lightamount transmitted through the liquid crystal display panel 804increases, and hence the viewing angle can be widened, and hence therange in which the two-dimensional image is recognizable can be widened.

Although drive of the light emitting device 810 as a main light sourceis set to a predetermined duty ratio in the above-described embodiment,in the case in which the viewer is “present” in the three-dimensionalimage recognizable zone, the light emitting device 810 may be driven atthe maximum brightness.

Alternatively, as shown in FIG. 5, the one or a plurality of auxiliarylight sources 814 may be a surface light source 814A, and in this case,the viewing angle can be widened by increasing the brightness whendisplaying the two-dimensional image.

It must be understood that the embodiment disclosed in thisspecification is not intended to limit the invention, and is disclosedsimply as an example at all events. The scope of the present inventionis not defined by the description described above, but defined byclaims, and all the modifications covered within the claims andequivalent thereto are included in the invention.

1. An image display system comprising a liquid crystal display panelbeing irradiated by a backlight and having a left eye image area and aright eye image area on a display area respectively, optical means forallowing light from the backlight to be transmitted to the left eyeimage area and the right eye image area and causing the transmittedlights from the respective image areas to enter into a left eye and aright eye of an viewer independently, and image parallax switching meansfor selectively displaying a three-dimensional image which causesparallax between the both eyes of the viewer when showing athree-dimensional image to the viewer or a two-dimensional image whichdoes not cause parallax between the both eyes when showing atwo-dimensional image to the viewer on the display area, characterizedin that an one or a plurality of auxiliary light sources for irradiatingthe liquid crystal display panel and causing the irradiated light to betransmit through the left eye image area or the right eye image area andenter into the both eyes of the viewer and light source control meanswhich turns on the backlight when showing the three-dimensional image tothe viewer, and turns on the one or a plurality of auxiliary lightsources when showing the two-dimensional image to the viewer areprovided.
 2. The image display system according to claim 1,characterized in that when the image parallax switching means switchesthe image to be shown to the viewer from the three-dimensional image tothe two-dimensional image, the one or a plurality of auxiliary lightsources are turned on by the light source control means after switchingto display from the three-dimensional image to the two-dimensional imageby the image parallax switching means.
 3. The image display systemaccording to claim 1 or 2, characterized in that when the image parallaxswitching means switches the image to be shown to the viewer from thetwo-dimensional image to the three-dimensional image, the display isswitched from the two-dimensional image to the three-dimensional imageby the image parallax switching means after turning off the one or aplurality of auxiliary light sources by the light source control means.4. The image display system according to any one of claim 1 to claim 3,characterized in that the light source control means turns off or dimsthe backlight when the one or a plurality of auxiliary light sources areturned on.
 5. The image display system according to any one of claim 1to claim 3, characterized in that the light source control means alsoturns on the backlight when turning on the one or a plurality ofauxiliary light sources.
 6. The image display system according to anyone of claim 1 to claim 5, characterized in that the one or a pluralityof auxiliary light sources are higher in brightness than the backlight.7. The image display system according to any one of claim 1 to claim 6,characterized in that the backlight is disposed between the liquidcrystal display panel and the one or a plurality of auxiliary lightsources.
 8. The image display system according to any one of claim 1 toclaim 7, characterized in that the one or a plurality of auxiliary lightsources are composed of one or a plurality of surface light source. 9.The image display system according to any one of claim 1 to claim 8,characterized in that viewer detection means for detecting existence ofthe viewer is provided, and the light source control means turns on theone or a plurality of auxiliary light sources when the existence of theviewer is not detected by the viewer detection means.